<template>
    <div class="scroll-container" ref="scrollContainer" @wheel.prevent="handleScroll">
        <div class="scroll-wrapper" ref="scrpllWrapper" :style="{left:left+'px'}">
            <slot></slot>
        </div>
    </div>
</template>
<script>
const padding = 15
export default {
    name:'scrollPane',
    data(){
        return{
            left:0
        }
    },
    methods:{
        handleScroll(e){
            const eventDelta = e.wheelDelta || -e.deltay * 3
            const $container = this.$refs.scrollContainer
            const $containerWidth = $container.offsetWidth
            const $wrapper = this.$refs.scrollWrapper
            const $wrapperWidth = $wrapper.offsetWidth
            if (eventDelta > 0) {
                this.left = Math.min(0, this.left + eventDelta)
            } else {
                if ($containerWidth - padding < $wrapperWidth) {
                if (this.left < -($wrapperWidth - $containerWidth + padding)) {
                    this.left = this.left
                } else {
                    this.left = Math.max(
                    this.left + eventDelta,
                    $containerWidth - $wrapperWidth - padding
                    )
                }
                } else {
                this.left = 0
                }
            }
        },
         moveToTarget ($target) {
            const $container = this.$refs.scrollContainer
            const $containerWidth = $container.offsetWidth
            const $targetLeft = $target.offsetLeft
            const $targetWidth = $target.offsetWidth

            if ($targetLeft < -this.left) {
                // tag in the left
                this.left = -$targetLeft + padding
            } else if (
                $targetLeft + padding > -this.left &&
                $targetLeft + $targetWidth < -this.left + $containerWidth - padding
            ) {
                // tag in the current view
                // eslint-disable-line
            } else {
                // tag in the right
                this.left = -($targetLeft - ($containerWidth - $targetWidth) + padding)
            }
        }
    }
}
</script>
<style rel="stylesheet/scss" lang="scss" scoped>
.scroll-container {
  white-space: nowrap;
  position: relative;
  overflow: hidden;
  width: 100%;
  .scroll-wrapper {
    position: absolute;
  }
}
</style>